Creating Motion Graphics with After Effects, 5th Edition

10 All About Masking

Masking tools create transparency using standard or freeform Bezier shapes

Not all footage items look best full frame. And not all come with their own alpha channels to block out the parts you don’t want to see. Therefore, we often use masks to “cut out” the alpha channels we require. You can create masks in a variety of ways: You can draw a path using the mask tools in either the Layer or Comp panel, specify the dimensions numerically, or paste a path created in Illustrator or Photoshop.

We’ll start this chapter by drawing and editing simple geometric mask shapes, then feathering their edges. We’ll continue by drawing Bezier and RotoBezier masks, then offer tips and techniques for animating and modifying masks. We’ll be ...